I would say we have one but you can divide that into about as many pieces as you like.

As a geologist, I look at it as continental plates floating around on the mantle with the oceanic plates forming an ephemeral crust beneath the ocean which covers most of the earth.

1

5

We have five oceans:

1.Pacific Ocean

2.Atlantic Ocean

3.Indian Ocean

4.Southern Ocean aka Antarctic Ocean

5.Arctic Ocean

Five

just one

How gigantic can laziness get?